EFFECT OF TESTOSTERONE AND GONADOTROPHIN INJECTIONS ON THE SEX ORGAN DEVELOPMENT OF ZINC-DEFICIENT MALE RATS

Abstract

Zinc-deficient rats, receiving a diet low in zinc (0.5 μg zinc/g), were injected subcutaneously with testosterone propionate or gonadotrophins for periods of 13 to 28 days.The hormone injections in every case caused marked growth of accessory sex organs of zinc-deficient rats. The zinc concentrations of the large hormone-stimulated dorsolateral prostate glands were very low and similar to those of glands in untreated zinc-deficient rats. Testosterone propionate did not alter the testicular atrophy which had occurred before treatment. Gonadotrophin increased the rate of growth and possibly the rate of maturation of testes that were immature prior to treatment. When the testes had matured and were producing sperm before treatment, the tubular atrophy that is typical of zinc deficiency developed in spite of the injected gonadotrophins.Testicular atrophy in zinc-deficient rats is probably due specifically to an inadequate supply of zinc to the testis. The availability of sufficient zinc for incorporation of high concentrations into sperm seems to be essential for the maintenance of spermatogenesis and the survival of the germinal epithelium. On the other hand, the reduction in rate of growth and development of immature testes and of all accessory sex organs in zinc-deficient rats is due mainly to an inhibition of pituitary gonadotrophin output.